Various strap like devices are known for mounting a body to a channel having a restricted mouth. One problem is to provide suitable attachment members for connecting the strap to the channel. Such attachment members are conveniently and cheaply made from sheet steel, but with soft aluminium channels the thin sheet can cut into the aluminium. Also conventional attachment members are usually not easily adaptable to different sizes of channel. Another problem is coping with a wide variety of different size and shape bodies to be fixed to the channel. Yet another problem is that of providing adequate strength in the mounting and reducing the risk of accidental, or even deliberate but unauthorised, detachment of the device from the channel.